Gable top container with pull tab

ABSTRACT

A boxed end container is shown having one end closed by a transverse ridge seal and carrying a pull tab. The pull tab allows a separating force to be applied to the ridge seal of the sealed container to separate at least part of the ridge seal and thus open the container and allow discharge of its contents. The pull tab is a generally planar member having an axially extending shank member with a proximal end portion which can be gripped and pulled by a user and a distal end portion having foot members extending transversely to each side of thereof. The shank and foot members are substantially co-planar with one another. The pull tab is secured by the foot members externally to a wall of the container at or adjacent to the ridge seal of the container.

BACKGROUND TO THE INVENTION

Many materials, notably fluids such as milk or fruit juices, liquiddetergents or fabric softeners and mineral or vegetable oils, andpowders such as detergent powders (for convenience collectively denotedhereinafter as fluids), are put up in sealed containers for transportand storage prior to use, when the container is opened and the contentsdischarged. Many forms of containers are used for this purpose, but oneform is a thin walled carton made from a thin card or plastic sheetmaterial and having a generally squared or rectangular cross-section anda cuboid or brick-like overall shape. The contents of such a containerare typically fed to the container through an open top end of thecontainer, the other end being having been closed by folding over thebasal portion of the side walls to form a boxed end to the container.When the desired amount of material has been fed to the container, theopen top of the container is closed by forming transversely directed Vfolds in the upper portions of two opposed side walls, with the apexesof the Vs directed inwardly towards one another. This has the effect ofbringing the top portions of the other two side walls of the containertogether to form a tented top to the container having a ridge lyingalong the line of indentation of the V folds. The ridge is then heatsealed or otherwise processed so as to secure together the opposed facesof the upper portions of the V folded and other side walls in a singlelinear transverse strip seal closure to the container, at least themajor portion of the closure being located within the overallcross-sectional plan area of the container.

The sealed ridge is often then folded down about a transverse fold lineextending across approximately the midpoint of one of the side walls ofthe tented top, so as to form a flat boxed end to the container. In someforms of such a closure, a tape, which can be wire-reinforced, isincluded in the line of the ridge, for example during folding over ofthe ridge material. This tape extends beyond the ends of the ridge toprovide extensions which can be bent over to secure the folded downridge in position by engaging the free ends of the tape under the lipformed along the edge of the boxed end where the V folded portion of thecontainer wall is indented. Alternatively, the free ends of theextensions can be adhered or otherwise secured to the side walls of thecontainer once the ridge has been folded down, to form a boxed end tothe container.

For convenience, the following terms will have the following meansherein:

boxed end openable containers are containers of the above describedgeneral type;

ridge seal will be used to denote the transverse linear seal between theopposed faces of the top end portions of the indented and non-indentedside walls of the container;

ridge will be used to denote the exposed top edge of the ridge seal orthe edges of the wall material which have been brought together prior toforming the ridge seal;

ridge structure will be used to denote the structure formed by bringingtogether the top end portions of the side walls of the container andwhich have been or are to be secured together by heat sealing, welding,adhesion or other means between opposing faces at the interfaces betweenthose opposing faces to form the ridge seal;

gabled end will be used to denote the structure formed at the top end ofthe container by indenting the upper portions of two opposed side wallsof the container to form the V folds in the ridge structure;

tented end will be used to denote the end of the container with theridge in the raised position either before or after forming the ridgeseal;

gabled side walls will be used to denote the upper portions, usuallythree triangular portions, of the two opposed side walls of the open endof the container which have been indented by forming a V or other axialfold in the upper portion of the side wall so that the wall is collapsedlaterally inwardly to form the gabled end to the container;

gable end triangles will be used to denote the triangular shaped wallsforming the exposed surfaces within the gabled end of the container;

tent side walls will be used to denote the two opposed side walls of thecontainer which extend between the gabled side walls of the gabled endof the container;

wet wall will be used to denote an internal surface of the containerwhich is to be in contact with the contents of the container, includingthe upper portions of such walls which are to be incorporated into theridge structure;

dry wall will be used herein to denote an external surface of thecontainer which is not in contact with the contents of the container,including the upper portions of such walls which are to be incorporatedinto the ridge structure.

To open such a boxed end openable container, the seal in the gabled endat the interface between the opposing dry wall surfaces of the V fold atone end of the linear ridge seal is separated. This forms a pair ofwings in the gabled end so that the plan view configuration from aboveof the ridge seal to the container adopts a Y shaped configuration inplace of a single line seal. The top edges of the wings forming the headof the Y remain sealed together so that the container is still sealedwhen the ridge seal adopts this configuration. The wings are then bentbackward to lie in line with each other, ie. so that the plan viewconfiguration from above of the ridge seal adopts a T shapedconfiguration with the wings forming the head of the T. The free ends ofthe wings are then pressed inwardly towards the centre line of theupright of the T to apply a separating force to the seal at theintersection of the head and the upright of the T. This is intended tocause the seal between the opposed faces of the wet walls at the top ofthe container to separate at this intersection and to form an openingthrough which the contents of the container can be discharged. In somecases it may be desired to bend the wings beyond the in-lineconfiguration to form a Y plan shape having an inverted head (theinverted Y configuration), so as to enhance the separating force appliedto the seal at the intersection upon the application of pressure to thefree ends of the wings.

However, separation of the seal at the intersection is often incompleteand/or the wings collapse so that the user cannot continue to apply theseparating force to the seal. It is therefore usually necessary for theuser to insert a finger tip, knife point or other implement into theinitial opening formed at the intersection to assist full separation ofthe seal to be achieved and the opening then extended to form a spoutoutlet to the container.

In many cases the initial separation of the seal between the wet wallsat the intersection of the head and upright of the T is insufficient toform an aperture into which the user can insert a finger tip. It is thennecessary for the user to pinch the dry wall material in the region ofthe intersection and to try to pull the wall outwardly to causeseparation of the seal at the intersection. Such separation of the sealmay occur abruptly, causing spillage of the contents of the container,and the need for such additional operations to separate the ridge sealis inconvenient.

Notwithstanding these problems in forming the opening to the container,which are particularly acute for the aged or infirm and for children,boxed end openable containers provide a simple and effective containerfor the storage and transport of a wide range of fluids and remainwidely used.

Many attempts have been made to resolve the difficulties in opening suchcontainers by incorporating string pulls or the like into the linearseal at the gabled end of the container, see for example U.S. Pat. Nos4,883,222, 4,821,950 and 4,874,126, European Application No. 0 695 264Aand British Patent Application No 2,010,212A. However, in all cases oneor more additional components have to be incorporated into the ridgestructure. This introduces problems in accurate positioning of thiscomponent and securing it in position. It also introduces an additionalmember between the walls which are to be sealed together to form theridge seal, which may result in weakening of the seal in this area, withthe attendant risk of premature failure of the ridge seal. In addition,the material from which the additional component is formed oftenundergoes thermal fusion when the ridge seal is formed by a heat sealingprocess. This can cause the additional component to fuse together and/orto exposed wall surfaces of the container, causing the component to snapwhen pulled and/or to create additional sealing adjacent the ridge sealwhich has to be separated in order to open the container. The additionalcomponent is often secured in register with what is to become thepouring spout to the opened container. The contents of the containerthen flow over the component which may have been exposed to dirt, greaseor other materials and thus cause contamination of the contents.Furthermore, in order to introduce the additional components into theridge seal it is necessary to modify the carton construction, fillingand sealing processes considerably, which adds to the capital andoperating costs required to implement such proposals. None of theseproposals has been adopted commercially.

It has also been proposed in for example U.S. Pat. No. 3,520,464, PCTApplications Nos. WO96/29253 and WO97/44255 and British PatentApplication No. 2,253,608A to secure a pull tab or the like to one ormore of the gable end triangular wall sufaces of the gabled end of thecontainer. Whilst such a proposal may overcome the problems in securingan additional component within the ridge structure, such proposals havenot been adopted. This is due to failure of the anchorage of the pulltab to the wall of the container when tension is applied to it to openthe container, even where the ridge seal is partially separated to adoptthe T plan configuration as described above. As a result, the pull tabseparates from the container before the ridge seal is separated and thecontainer remains sealed. Even if the area of the foot of the pull tabwhich is anchored to the wall of the container is increased, the maximumarea which can be achieved is restricted by the available area of thetriangular wall(s) to which the foot is attached and the maximum size ofthe pull tab which can be accepted before it interferes with themechanical handling of the carton during filling and transport, andremoval of the pull tab before the ridge seal separates still occurs.

In place of additional components to provide the pull tab, it has beenproposed, for example in European Patent Application No. 0 087 839A andPCT Application No. WO82/03370, to provide the pull tabs as axialextensions of part of the walls of the container. However, suchextensions are usually located at what will be the pouring spout of theopened container, which results in contamination of the contents aspointed out above. Furthermore, if such axial extensions are folded tolie flat against the outside wall of the container, so as to avoid theirbecoming snagged in the container forming or filling machinery, at leastpart of the extension will be incorporated into the ridge structure andwill become fused within the ridge seal as the container is sealed. Thiscan so weaken the pull tab that it breaks away from the ridge sealand/or the tab becomes fused within the ridge seal. This can lead toadditional seals which require separation in order to open thecontainer.

It has also been proposed to weaken the adhesive bond within the ridgeseal so that less force is required to separate the seal and thus openthe container. For example, it has been proposed to apply an abhesive toparts of the wet walls within the ridge structure so that they do not,or only weakly, adhere to one another during the container sealingoperation. However, the use of abhesives requires accurate placement ofthe correct amount of the abhesive at the desired locations within theridge structure so that only a very weak seal is formed within thegabled end. This introduces additional operations and costs in themanufacture of the sealed container and inherently carries the attendantrisk that the seal will fail prematurely during storage, transport orhandling by the end user. In order to reduce this risk, it has beenproposed in U.S. Pat. No. 4,946,041 to use a specially sculptured heatsealing bar to omit sealing of areas within the ridge seal itself.However, this requires the use of complex additional heat seals andaccurate formation of the non-sealed areas and also carries the inherentrisk of premature failure of the ridge seal.

It has also been proposed, for example in U.S. Pat. No. 3,204,850 and GBPatent No. 689,204, not to form a ridge seal by bonding togetheropposing faces within the ridge structure, but to form a labyrinthinemechanical seal by folding over the ridge structure and securing thefolded structure in position by a wire or adhesive. Such proposals aresusceptible to leakage of the container since no bonded seal is formed.Furthermore, such proposals require the use of specialist foldingequipment and cannot be carried out on conventional containermanufacturing equipment.

Rather than weaken the ridge seal or introduce additional componentsinto the ridge structure, it has been proposed to form lines of weaknessor actual cuts through the container wall and to cover those with aremovable cover strip, see for example GB Application No. 2,253,608A andU.S. Pat. Nos. 3,456,328 and 2,687,840. Removal of the cover stripexposes the cut or line of weakness which can then be separated to forman opening to the container. In a variation of such proposals, the wallof the container is partially cut through so that the wall can be tornat this point to form an outlet spout without the need to separate theridge seal or to form a pull tab from the wall of the container whichcan then be used to separate the ridge seal, see for example U.S. Pat.Nos. 2,470,199, 5,067,613 and 5,516,037. Such deliberate weakening ofthe container wall carries the inherent risk of premature failure of thecontainer.

However, none of the above proposals has proved technically orcommercially viable and, as a result, no satisfactory method for openingthe gabled end of a boxed end container exists in commerce. Despite theknown and much publicised problems with opening a boxed end container,such containers continue to be widely used because of their simplicity,low cost and ease of production and general acceptance by the public.

Surprisingly, we have found that if the foot of a pull tab secured to awall of the container is secured in a specific manner, the problems dueto separation of the pull tab from the container wall before theseparation of the ridge seal occurs can be reduced.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides a boxed end container havingone end closed by a transverse ridge seal and carrying a pull tabwhereby a separating force can be applied to the ridge seal of thesealed container so as to separate at least part of the ridge seal andthus open the container and allow discharge of its contents, which pulltab comprises a generally planar member having an axially extendingshank member with a proximal end portion adapted to be gripped andpulled by a user and a distal end portion having foot members extendingtransversely to each side of thereof, the shank and foot members beingsubstantially co-planar with one another, the pull tab being secured bythe foot members externally to a wall of the container at or adjacent tothe ridge seal of the container, characterised in that:

a the foot members are secured substantially symmetrically about thelongitudinal axis of the shank member to a wall of the container and/orto that portion of a wall incorporated into the ridge seal; and

b. the pull tab has a point of rotation about which the shank memberflexes with respect to the foot members when tension is applied to theproximal end of the shank member during opening of the container, whichpoint of rotation is located longitudinally with respect to the shankmember substantially in register with the junction of the shank memberand the proximal edges of the foot members; and

c. the securement of each of the foot members to the container wall isby means of a securement means which presents an edge proximal to thepoint of rotation which edge is configured so that at least a portionthereof extends normal to a line extending from said proximal edge tosaid point of rotation, said line intersecting said edge intermediatethe ends thereof.

The term edge is used herein with respect to the securement means todenote the periphery of the securement means extending in the plane ofthe wall of the container.

Preferably, the securement is by means of a heat seal between thesurface layers of the container wall and the material of the pull tab.Surprisingly, we have found that such heat seals can be in the form ofline seals rather than seals extending over the full plan areas of theopposed faces of the container wall and the foot members of the pulltab. It is most unexpected that reducing the area over which the footmember is secured to the container wall does not weaken the securementof the pull tab to the container.

Accordingly, the present invention also provides a boxed end containerhaving a pull tab secured externally to a wall of the container at oradjacent to the ridge structure of the container whereby a separatingforce can be applied to the ridge seal of the sealed container,characterised in that the distal end of the pull tab is securedexternally to an external wall of the container and in that securementof the distal end is by means of at least two lines of securement, oneto each side of the longitudinal axis of the shank of the pull tab, eachof which lines of securement have at least a portion thereof which isconfigured so that it extends normal to a line extending from the pointof rotation of the shank of the pull tab and intersecting the line ofsecurement intermediate the ends thereof. We believe that such aconfiguration ensures that the portion of the line of securement mostclosely adjacent to the point of rotation of the shank member isorientated substantially at right angles to the forces transmitted fromthe shank member to the foot members and thus acts as a stop to anypeeling separation of the securement from the container wall.

In a particularly preferred embodiment, the foot members are secured tothe container wall so that the securement area for each foot extendslongitudinally both above and below the point of rotation of the shankof the pull tab. We have found that such a form of securement reducesthe risk that the securement undergoes progressive peel separation asthe proximal end of the pull tab is lifted away from the plane of thecontainer wall and tension applied thereto.

Accordingly, the present invention also provides a boxed end containerof the invention, characterised in that the distal end of the pull tabis secured to a wall of the container by means of a securement area orareas, at least one lying to each side of the longitudinal axis of theshank of the pull tab, the securement areas extending longitudinally toeach side of the point of rotation of the shank of the pull tab.Preferably, the securement areas extend a distance d above (distallybeyond) the point of rotation and a distance d′ below (proximally shortof) the point of rotation and the ratio of d:d′ has a value of from 10:1to 1:10, preferably about 1:3 to 3:1, notably about 1:1.

We believe that a pull tab having the configuration required to achievesuch a form of securement to the container wall is novel. The inventiontherefore also provides a pull tab for use upon a container, which pulltab comprises a generally planar member having a proximal portionadapted to be gripped and pulled by a user, a longitudinally extendingshank member and a distal portion by which the pull tab can be securedto a wall of a container or a blank for use in the manufacture of acontainer, characterised in that the distal portion is provided with twofoot members extending laterally to each side of the longitudinal axisof the shank member, each foot member extending proximally and distallylongitudinally to either side of the point of rotation of the shankmember

We have further found that the provision of an area between the footmembers which is not secured to the wall of the container can beadvantageous in that it allows the shank and the junction between theshank and the foot members to lift off the surface of the walls as the Vfolds are formed therein during the sealing of the container. Thisreduces the severity of the folding which the pull tab has to undergoand minimises the formation of a set in the material of the pull tabwhich could affect the way in which the pull applied to the proximal endof the pull tab is transferred to the foot members. The lack ofsecurement between the foot members also allows to foot members to movelaterally towards each other as pull is applied to the proximal end ofthe pull tab. This causes the foot members to apply two opposing forcesacting along the line of the ridge so as to develop a rolling peelingseparation of the ridge seal. The application of such a peeling forcemore readily achieves separation of the ridge seal than a shear force.

Accordingly, the present invention also provides a boxed end containerhaving a pull tab secured externally to a wall of the container at oradjacent to the ridge structure whereby a separating force can beapplied to the ridge seal of the sealed container, characterised in thatthe distal end of the pull tab is secured to an external wall of thecontainer and in that securement of the distal end is by means of twolaterally spaced apart portions of the distal end portion of the pulltab with an intermediate unsecured portion located between the securedportions, whereby the pull tab exerts two opposing forces upon thatportion of the ridge seal axially in register with said intermediateunsecured portion when a user pulls upon the pull tab.

The pull tab for present use comprises a shank member having a proximalend by which a user can grip and pull the tab, and a distal portion bywhich the shank is secured to the container. The transverse dimension ofthe shank is enlarged at the distal portion of the shank so as toprovide laterally extending foot members which are secured to thecontainer. The intermediate area of the distal end of the shank may ormay not be secured to the container. Typically, the foot members extendfrom 1 to 5 cms to either side of the shank of the pull tab and extendat any suitable angle from the shank to provide the required d:d′ ratiofor the securement areas by which the foot members are secured to thewall of the container. We have found that the included angle between theproximal edges of the foot members and the longitudinal edges of theshank member should be less than 90°, preferably from 15 to 80°, notablyabout 45°, so that the forces exerted on the foot members when the shankis pulled by a user do not act to peel the securement from the containerwall. Such angles also permit the edges of the areas or lines ofsecurement to adopt the desired orientation within the plan area of thefoot members.

The longitudial edges of the shank may intersect the line of theproximal edge of each foot member at a sharp angle. However, it ispreferred to provide a radiussed intersection extending over from 1 to 5mms of the longitudinal length of the shank. Such radiussing provides astop to any tearing of the material of the pull tab in this location andalso allows the material of the pull tab to deform in this area duringformation of the V folds of the gabled end of the container and also toreduce the lifting of the proximal edge of the foot members and thusreduce the peeling force acting on the securement of the foot members tothe container wall. When determining the position of the point ofrotation of the shank member, allowance needs to be made for suchradiussing. In general we find that when designing the shape of the pulltab it is satisfactory to assess the point of rotation as being halfwaybetween the longitudinal points along the axis of the shank member wherethe radiussing begins and ends. However, it will be appreciated that thepoint of rotation will move distally towards the end of the radiussingwhen the pull tab is lifted and pulled by a user so that the point ofrotation has a rest position and an extreme in use position which issubstantially in register with the distal end of the radiussing.

The term point of rotation of the shank member is therefore deemed toinclude both the rest and extreme in use positions. A particularlypreferred form of pull tab is a generally T shaper planar member havinga triangular finger ring at its proximal end joined by a shank member toa pair of generally triangular shaped foot members which extendlongitudinally for substantially the same distance to either side of thepoint at which the feet join the shank member. The opposing edges of thefinger ring and the foot members are substantially parallel to oneanother and are inclined at substantially 45° to the longitudinal axisof the shank member.

It is also preferred to provide the proximal portion of the pull tabwith a finger hole, ribbing or other means by which a user can grip thepull tab. Such forms of pull tab can be made using conventional cutting,stamping or other equipment and techniques.

The pull tab can be made from a number of materials, depending upon themethod used to secure the foot members to the container wall.Preferably, the pull tab is secured by heat or ultra sonic welding andthe pull tab is made from a material which readily welds to thecontainer wall. Thus the pull tab can be cut from a sheet ofpolyethylene or other low temperature fusing thermoplastic material.Where the pull tab is secured to the container wall be a hot meltadhesive, a pressure sensitive adhesive or double sided adhesive tape,it may be desired to subject the polyethylene to corona discharge orother treatment to render it receptive to the adhesive. However, we havefound that polyethylene may not have the tensile strength required toapply sufficient force to the seal of the container without itselftearing. A particularly preferred material is a laminated materialhaving one exposed face formed from a polyethylene which can bethermally bonded to the material of the container wall, and one or moreplies of a high tensile material, for example a polyester. It isparticularly preferred that the other exposed face of the laminate isformed from a material which has a fusion point higher than, preferablyat least 40° C. higher than, the fusion point of the surface layer ofthe container wall so that this face does not significantly fuse duringthe formation of the ridge seal to the container. Polyester, which has afusion temperature about 100° C. higher than that of polyethylene, isparticularly preferred. The use of such a laminate material reduces therisk of the exposed faces of the pull tab bonding to one another and/orto the container wall during the heat sealing of the ridge seal

The pull tab can be secured to the container at any position on a wallof the container or within the ridge structure at which the securedportions of the pull tab can exert the separating force on a portion ofthe ridge seal axially in register with the pull tab. However, in orderthat the forces generated as the shank of the pull tab is pulled by auser can exert sufficient force on the ridge seal, it is preferred tosecure the pull tab within 2.5 cms of the foot of the ridge seal. Thus,the pull tab can be secured to a tented side wall of the end of thesealed container or to the exposed side wall of the linear ridge seal.However, it is particularly preferred to secure the pull tab to a gabledend wall of the container so that the container is opened in a mannersimilar to a conventional carton. For convenience, the invention will bedescribed hereinafter in terms of this preferred position of securement.

The distal end of the pull tab may be incorporated within the ridgestructure. Since the distal portions of the pull tab are attached toopposing dry wall faces of this portion of the ridge seal, they do notimpair the integrity of seal between the opposing wet walls of the ridgeseal. However, securing the pull tab within the ridge structure mayresult in excessive creasing of that part of the distal end of the pulltab within the V fold of the ridge seal. This may require the provisionof abhesive or other means to prevent significant adhesion of thatintermediate portion of the pull tab to the opposing portions of theridge structure during heat sealing of the ridge structure duringclosing of the container after filling. It is therefore preferred thatthe laterally extending feet of the pull tab be secured to one or moreof the portions of the gabled end wall of the container below the ridgeseal itself. The securement can be to the central triangular portion ofthe gabled end wall. However, this may require that the securement beaxially removed some distance from the foot of the ridge seal and thusthat the forces generated by the pull tab do not act directly upon theridge seal and their effect on the ridge seal is reduced. It istherefore particularly preferred that the pull tab be secured to theside roof triangle walls of the gabled end wall and, preferably, not tothe central triangular end wall of the gabled end wall. By securing thepull tab in this manner, once the end of the linear ridge seal had beenseparated as described above for the initial stage of opening the cartonto form a T or Y plan view seal, the forces applied by the pull tab tothe ridge seal exert a peeling action on the ridge at the intersectionof the upright and head of the Y or T which causes the ridge seal toseparate readily at this point. A force is also generated transverse tothe line of the ridge seal, bowing the gable end wall outwardly to formthe outlet spout to the container and progressively separating the ridgeseal to either side of the intersection. As a result, a pull tabanchored in this manner is surprisingly more resistant to detachmentfrom the container wall than one anchored to the central triangle wallor within the ridge seal structure as with the prior art proposals.

Accordingly, from another aspect, the present invention provides a boxedend container of the invention, characterised in that the foot membersof the pull tab are secured to the gabled end triangular roof portionsof the gabled end of the container. Preferably the portion of the distalend of the shank member intermediate the foot members is not secured tothe container wall.

The container may be made from a wide range of materials, for examplewax coated card, polymer coated card or a laminated plastic sheetmaterial. However, the invention will be described hereinafter in termsof a conventional gable ended container made from a polyethylene orother thermoplastic polymer laminated card. Such containers can be madeby folding and securing the appropriate opposing edges of a flat blankusing conventional techniques and equipment. Whilst the pull tab can beapplied at any suitable point during the manufacture of the container orits blank or during the filling and sealing of the assembled container,it is preferred to secure the pull tab to the blank prior to assembly ofthe container using a conventional heat sealing technique.

The invention thus also provides a blank for use in the construction ofa boxed end openable container of the invention, which blank comprises aseries of connected panels adapted to be folded and secured to oneanother so as to form the container, the terminal portions of two ofsaid panels being adapted to form the gable end walls of the assembledcontainer, characterised in that at or adjacent the terminal portion ofone or more wall panels there is secured a pull tab comprising agenerally planar member having a proximal end adapted to be grasped andpulled by a user, an axially extending shank member and a distal endportion having foot members extending transversely to each side thereofby which the pull tab is secured to a panel of the blank by means ofsecurement means, characterised in that the securement means presents anedge proximal edge to the point of rotation of the shank member andconfigured so that at least a portion of the edge extends normal to aline extending from the point of rotation to intersect the edgeintermediate the ends thereof.

Preferably, each of said terminal portions of said two panels are toform the gable end walls of the container and is provided withsubstantially symmetrical fold lines forming a V having its apex at oradjacent the centre point of the terminal edge of the panel and its baseat or adjacent the intended base of the gable end wall so as to definetwo laterally outward triangular areas and an intermediate triangulararea of said terminal portion; and the foot members of the pull tab aresecured to each of the laterally outward triangular portions of at leastone of said terminal portions.

Preferably, the pull tab is located axially symmetrically about thecentre line of the panel and substantially in register with that portionof terminal portion of the panel which is to form the apex of the V foldin the gable end of the assembled container.

The pull tab can be applied to the container blank using any suitabletechnique, for example a rotary or linear label application techniqueusing a tack weld, adhesive or other means to secure the pull tab inposition initially; and thereafter apply a subsequent full heat weld tosecure the pull tab in position. However, it will usually be desired tosecure the pull tab in position with a single full heat weld in a singlepass through the pull tab application and securing process.

For convenience, the securement of the pull tab to the container will bedescribed in terms of the heat welding of the foot members of the pulltab to the appropriate areas of the blank from which the container issubsequently manufactured. The heat welding is conveniently achieved bya conventional heat sealing technique.

As stated above, the heat weld can extend over the plan area of the footmember, but preferably is in the form of one or more line welds betweenthe foot member and the wall material of the container. The ability touse line welds to secure the foot members to the container wall reducesthe risk of thermal damage to the pull tab and enables the pressurerequired for the heat welding to be applied over small areas, thusreducing the power requirements for the heat welder. Such line welds canbe simple continuous or discontinuous straight lines or can form arectangle or other shape enclosing an unwelded area. The welds may alsofollow curved lines and a particularly preferred form of weld line is anarc centred upon the point of rotation of the shank of the pull tab sothat all forces generated by pulling the proximal end of the pull tabare applied substantially normally to the line of the weld. If desired,several line welds may be formed at progressively increasing distancesfrom the point of rotation.

As indicated above, the welded areas preferably extend longitudinallyboth above (that is proximally of) and below (that is distally of) thepoint of rotation of the shank of the pull tab. Preferably, at least onewelded area to each side of longitudinal axis of the shank of the pulltab extends continuously from above to below the point of rotation andhas an edge proximal to the point of rotation which subtends over atleast a portion of its length an included angle to the longitudinal axisof the shank which is from 20 to 80°, preferably about 45°. It isparticularly preferred that the edges of the lines or areas ofsecurement are adjacent to and substantially parallel to the fold linesdefining the boundaries between the three triangular portions of thegabled end of the container so that the forces applied by the pull tabact directly to

The optimum form of the securement can readily be determined within theabove guidelines using simple trial and error tests.

In order to assist separation of the ridge seal, it may be preferred toprovide reduced adhesion between the opposed faces of the dry walls forat least a portion, typically from 10 to 50%, of the indentation of thev folds within the ridge seal. This can be achieved by applying anabhesive agent to selected areas of the opposing dry walls which are tobe incorporated into the ridge seal. Alternatively, such weakness in theridge seal can be achieved by extending part or all of the distal end ofthe shank and/or of the lateral foot members into the ridge structure.However, we have found that the location of the anchorage of the pulltab to the gable end triangular roof faces usually enables sufficientseparating force to be applied to the ridge seal without the need forany abhesion or other weakening of the ridge seal, thus reducing therisk of premature separation of the seal and failure of the container.

The above preferred form of container is readily opened by partiallyseparating one end of the linear ridge seal formed by the conventionalheat seal closure of the container and then applying tension to theproximal end of the pull tab.

Accordingly, the invention also provides a method for opening a boxedend openable container of the invention, which method comprisesseparating the seal between the dry walls at that end of the ridge sealof the container adjacent the pull tab, or deflecting the ends of theridge seal, so as to form a ridge seal having bowed or a T or Yconfiguration, and applying tension to the proximal end of the pull tabso as to separate the seal between the wet walls of seal, preferably atthe intersection of the upright and head of the T or Y configured seal.

We believe that, at least initially, the force applied to the wet wallsof the ridge seal by the pull tab is a peel force acting along the lineof the ridge seal at this point. However, the force will usually alsoinclude a component normal to the line of the seal which acts at leastin part upwardly towards the lower edge of the ridge seal and acts toimpart an upward peeling force upon the ridge seal which further aidsseparation of the ridge seal. Continued application of tension to thepull tab causes progressive separation of substantially the whole lengthof the seal to form a spout outlet to the container. If desired, thecontainer may be provided with one or more score or fold lines whichassist the bowing of the gable end walls and the associated side wall ofthe container to assist separation of the ridge seal and deployment ofthe spout outlet to the container. Such fold or score lines can beformed using conventional techniques and equipment.

The surfaces of the spout which are contacted by the dischargingcontents of the container, are those of the wet walls which have beenbonded together during sealing of the container and have not beenexposed to external contamination during storage and transport prior toopening of the container. Furthermore, since the pull tab is securedexternally to the container and does not form part of the lip of thespout, material flowing through the spout will not contact the pull taband will not thus be contaminated by grease, dirt etc on the pull tab.The containers of the invention can therefore be used for the packagingof foodstuffs and other materials which require to be held under sterileconditions and which must be subjected to the minimum of contaminationduring discharge from the container. Furthermore, since the containerand the pull tab can be made without any metallic components, thecontainers of the invention can be heated in a microwave oven. Thecontainers of the invention can thus be used to contain soups or other.foodstuffs which require heating before consumption. Since thecontainers can be readily and simply opened, risk of spillage of hotfoodstuff onto a user is reduced.

The invention thus provides a simple and effective solution to theproblem of opening a boxed end openable container without the need tomodify the container manufacturing or filling process significantly,thus enabling the invention to be applied to conventional equipment.Alternatively, the pull tab can be applied to an assembled or sealedcontainer using any suitable machine located at the end of the containerassembly, sealing or filling line.

DESCRIPTION OF THE DRAWINGS

To aid understanding of the invention, a preferred form thereof will nowbe described by way of illustration and with respect to the accompanyingdrawings, in which

FIG. 1 is a perspective view of the boxed end openable container in thefully closed configuration carrying a pull tab;

FIGS. 2, 3 and 4 shows the container of FIG. 1 with the ridge sealpartially opened, bent back to form the inverted Y configuration andwith the ridge seal separated to form a spout outlet to the container;

FIG. 5 shows a plan view of a blank for use in the construction of thecontainer of FIG. 1;

FIG. 6 shows an alternative version of the blank having additional foldlines to assist forming a full length spout to the side wall of thecontainer;

FIG. 7 shows the relationship of the edge of the heat sealed areasecuring the feet of the pull tab to the container wall to the point ofrotation of the shank member; and

FIGS. 8 to 10 show alternative forms of line seals for use in thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The container comprises a generally rectangular or square main bodyportion 1, whose bottom has been closed by conventional box folds orother means, and which contains milk, fruit juice or other fluid or afluent powder. The container is made from a wax or plastic coated paperor card so that it can readily be folded along score lines or the likeformed in a sheet blank from which the container is made and the foldedconfiguration secured in place by heat sealing or otherwise adhering theoverlapping edge portions of the assembled container. Alternatively, thecontainer can be made by blow or extrusion moulding a suitable plasticso that the container is formed as a unitary article with an open top.

Where the container is made from a flat blank, this is folded andsecured in its desired erected form by heat welding, adhesive or othersecuring techniques. For convenience, the invention will be describedhereinafter in terms of the use of a polyethylene or other thermoplasticpolymer coated card as is conventionally used in the manufacture of suchcontainers.

The upper, terminal portions of the side walls of the container havebeen folded in upon one another to form a conventional boxed end. Insuch an operation a V fold is formed in each of two opposed side wallswith the apex of each V directed towards the centre line of thecontainer. This has the effect of bringing the top edges of the othertwo side walls together to form a tented end to the container. The topedges of the side walls lie against one another to form a ridge 2 lyingalong a transverse line extending along the line of indentation of the Vfolds. The edges are sealed together by applying heat and pressure usinga conventional heat sealing bar or the like to form a comparatively deeptransverse seal closure along the ridge 2. The depth of this ridge sealis sufficient to incorporate the upper edges of the V folded walls toensure a fluid tight closure.

The indented portion of the end of the container is the gabled end 3 andcarries a pull tab 10. As shown in FIG. 2, the gabled end wall A carriestwo fold lines 4 and 5 forming a triangle with its apex at the point atwhich the wall A is folded to form the V fold as the gabled end to thecontainer is formed. To each side of these lines lie inverted triangularareas B which are to form the roof faces of the gabled end of theassembled container and have their bases along the foot of the upperterminal portion of wall A which is to be incorporated into the ridgeseal 2. Between these triangular areas B is another reversed triangulararea C. These areas can readily be seen in the blanks shown in FIGS. 5and 6.

A pull tab cut from a polyethylene/polyester laminate has a pull ring 11at the proximal end of a shank portion 12. Extending laterally from theshank portion are two symmetrical triangular feet 13. These are securedvia the polyethylene layer to the triangular areas B to either side ofarea C by heat welding or other means, for example adhesive or riveting.The securing extends over the shaded areas shown in the drawings and itwill be noted does not extend into the intermediate portion D of theshank between the feet 13. The central portion of the pull tab formedfrom shank 12 and ring pull 11 is not secured to the wall of thecontainer, but is free to bow away from the container during formationof the gabled end to the container and during sealing of the ridge seal.If desired, the proximal end of the ring pull 11 may be tack welded orotherwise temporarily secured to the wall of the container for transportand storage prior to use.

As shown in FIG. 7, the shank 12 flexes about a point D when the ringpull 11 is pulled. This point D is the point of rotation. The edge ofthe heat seals between the feet 13 and the walls B proximal to the pointof rotation D is located closely adjacent to and substantially parallelto the fold lines 4 and 5 so that the included angle between the edge ofthe heat seal and the longitudinal axis of the shank of the pull tab isabout 45°. A line drawn from the point of rotation D normal to the edgeof the heat seal intersects the edge between its ends and the seal actsas a stop to prevent peeling of the heat seal. The heat seal areaextends both distally beyond and proximally short of the point ofrotation and the ratio of d:d′ has a value of approximately 1:1.

Such a container can be assembled from a blank as shown in FIG. 5 usingconventional techniques and equipment.

In use, the seal between opposed dry walls along ridge 2 is separated atthat end adjacent the pull tab 10 as with a conventional container toproduce a ridge which has a T plan shape as shown in FIG. 2, having anupright U and wings W to the head of the T shape. The seal between theopposed wet walls of the wings is still intact and so the containerremains sealed. If desired, the ridge in the head of the T is bentbackwards as shown in FIG. 3 to form an inverted Y plan shape to theridge. The user then pulls upon the ring 11 to cause the ridge seal atthe intersection X of the upright U and the wings W to separate and formthe pouring spout 15. The pull tab 10 remains below the lip of the spoutand is not in contact with the content of the container, thus reducingthe risk of contamination of the content as they are discharged.

As shown in FIG. 4, the spout 15 is comparatively short. It maytherefore be desired to add the additional fold lines 20 shown in FIG. 6which extend from the apex of area C to the base of the container topermit the side wall of the container to bow outwards to form a spoutextending for the full height of the container, thus aiding smooth flowof material from the container.

Due to the location and orientation of the heat seals, the feet 13 donot readily separate from the wall material and the user can thus exertconsiderable force on the ridge seal without the feet detaching from thewall. By way of contrast, when the pull tab was in the form of a T sothat the heat seals securing the head of the T to the container wall didnot extend proximaly of the point of rotation D, the pull tab readilypeeled off the wall before the ridge seal was separated.

As shown in FIG. 8, the feet 13 are secured to the wall by line seals 20and the lines E from the point of rotation normal to the line of theheat seals intersect the line seal intermediate their ends. Such a formof attachment ensures that the pull tab remains secured to the containerwall whilst the ridge seal is separated. FIG. 9 shows a set of lineseals 30 and 31 conforming to the shape of the outline of the solid heatseal used in FIG. 1; FIG. 10 shows an arcuate line heat seal 40. Alsoshown dotted in FIG. 10 is a form of the feet 13 which have been cutaway to conform to the arcuate shape of the heat seal 40. All thesevariations of the heat seal of FIG. 8 provide good levels of attachmentof the pull tab to the container wall.

What is claimed is:
 1. A boxed end container having one end formed by infolding the terminal portions of two opposed side walls of the containerto form a gabled end having gable end triangular walls and a transverseridge structure at the upper end of the container and thus close theupper end of the container, the ridge structure being retained in theclosed position by bonding together contacting surfaces of the wallmaterial in the ridge structure to form a transverse ridge seal closureto the container, the container carrying a pull tab whereby a separatingforce can be applied to the ridge seal of the container so as toseparate at least part of the bonding of the ridge seal and thus openthe container to allow discharge of its contents, characterized in that:the pull tab comprises a shank member extending longitudinally between aproximal end portion adapted to be gripped and pulled by a user and adistal end portion, said shank member having two longitudinallyextending edges thereto; said distal end portion of said shank memberhaving foot members, at least one extending transversely to each side ofthe shank member, which are secured substantially symmetrically withrespect to the longitudinal axis of said shank member externally to awall of the container at or adjacent to the ridge structure of thecontainer, said foot members having a proximal edge which extends fromsaid longitudinal edge of said shank member, the shank member and thefoot members in their free state when not secured to the container beingsubstantially co-planar with one another; the shank member has a pointof rotation about which the shank member flexes with respect to the footmembers when tension is applied to the proximal end of the shank memberduring opening of the container, said point of rotation being locatedlongitudinally with respect to the shank member substantially inregister with the junction of the longitudinal edges of the shank memberand the proximal edges of the foot members; the securement of each ofthe foot members to the container wall is by means of a securement meanswhich presents a securement edge proximal to the point of rotation, saidsecurement edge being configured so that at least a portion thereofextends normal to a line extending from said securement edge to saidpoint of rotation, said line intersecting said securement edgeintermediate the ends hereof.
 2. A container as claimed in claim 1,characterized in that the securement of the foot members is by means ofa heat seal.
 3. A container as claimed in claim 2, characterized in thatthe securement means is in the form of one or more line heat seals.
 4. Aboxed end container as claimed in claim 1, characterized in thatsecurement of the foot members of the pull tab is by means of at leasttwo lines of securement, one to each side of the longitudinal axis ofthe shank of the pull tab.
 5. A container as claimed in claim 1,characterized in that the securement of the foot members of the pull tabis by means of a securement area or areas, at least one lying to eachside of the longitudinal axis of the shank member of the pull tab, thesecurement areas extending longitudinally with respect to the shankmember both distally and proximally about the said point of rotation. 6.A container as claimed in claim 5, characterized in that the securementareas extend a distance d distally beyond the point of rotation and adistance d′ proximally short of the point of rotation and the ratio ofd:d′ has a value of from 10:1 to 1:10.
 7. A boxed end container havingone end formed by in folding the terminal portions of two opposed sidewalls of the container to form a gabled end having gable end triangularwalls and a transverse ridge structure at the upper end of the containerand thus close the upper end of the container, the ridge structure beingretained in the closed position by bonding together contacting surfacesof the wall material in the ridge structure to form a transverse ridgeseal closure to the container, the container carrying a pull tab wherebya separating force can be applied to the ridge seal of the container soas to separate at least part of the bonding of the ridge seal and thusopen the container to allow discharge of its contents, characterized inthat: the pull tab comprises a shank member extending longitudinallybetween a proximal end portion adapted to be grasped and pulled by auser and a distal end portion, said shank member having twolongitudinally extending edges thereto; said distal end portion of saidshank member having foot members, at least one extending transversely toeach side of the shank member, which are secured substantiallysymetrically with respect to the longitudinal axis of said shank memberexternally to a wall of the container at or adjacent to the ridgestructure of the container, said foot members having a proximal edgewhich extends from said longitudinal edge of said shank member, theshank member and the foot members in their free state when not securedto the container being substantially co-planar with one another; theshank member has a point of rotation about which the shank member flexeswith respect to the foot members when tension is applied to the proximalend of the shank member during opening of the container, said point ofrotation being located longitudinally with respect to the shank membersubstantially in register with the junction of the longitudinal edges ofthe shank member and the proximal edges of the foot members; thesecurement of each of the foot members to the container is by means of asecurement means which extends longitudinally a distance d distallybeyond the point of rotation and a distance d′ proximally short of thepoint of rotation and the ratio of d:d′ has a value of from 10:1 to1:10.
 8. A container as claimed in claim 7, characterized in that thesecurement means is a heat seal.
 9. A container as claimed in claim 7,characterized in that the securement means is in the form of one or moreline heat seals.
 10. A container as claimed in claim 1 or 7,characterized in that a portion of the shank member intermediate thefoot members is not secured to the container wall.
 11. A container asclaimed in claim 1 or 7, characterized in that the foot members aresecured to the gable end triangular walls of the gabled end of thecontainer.
 12. A container as claimed in claim 1 or claim 7,characterized in that the pull tab is made from a laminate of twopolymeric materials, one having a fusion temperature at least 40° C.higher than the fusion point of the other.
 13. A container as claimed inclaim 1 or 7, characterized in that the pull tab is made from a laminateof polyester and polyethylene.
 14. A container as claimed in claim 1 or7, characterized in that the included angle between the said proximaledge of the foot member and the longitudinal axis of the shank member isfrom 15 to 80°.
 15. A blank for use in the manufacture of a carton asclaimed in claim 1, characterized in that the blank comprises a seriesof connected panels adapted to be folded and secured to one another soas to form the container, the terminal portions of two of said panelsbeing adapted to form the gable end walls of the assembled container,characterised in that at or adjacent the terminal portion of one or morewall panels there is secured by securement means a pull tab, said pulltab being a generally planar member comprising: a shank member extendinglongitudinally between a proximal end portion adapted to be grasped andpulled by a user and a distal end portion, said shank member having twolongitudinally extending edges thereto; said distal end portion of saidshank member having foot members, at least one extending transversely toeach side of the shank member, which foot members are securedsubstantially symmetrically with respect to the longitudinal axis of theshank member to said one or more wall panels, said foot members having aproximal edge which extends from said longitudinal edge of said shankmember; said shank member having a point of rotation about which theshank member is adapted to flex, said point of rotation being locatedlongitudinally with respect to the shank member substantially inregister with the junction of said longitudinal edges of the shankmember and said proximal edges of said foot members; and in that saidsecurement means presents an edge proximal edge to the point of rotationof the shank member, said securement edge being configured so that atleast a portion of thereof extends normal to a line extending from saidpoint of rotation to intersect said securement edge intermediate theends thereof.
 16. A blank for use in the manufacture of a carton asclaimed in claim 7, characterized in that the blank comprises a seriesof connected panels adapted to be folded and secured to one another soas to form the container, the terminal portions of two of said panelsbeing adapted to form the gable end walls of the assembled container,characterised in that at or adjacent the terminal portion of one or morewall panels there is secured by securement means a pull tab, said pulltab being a generally planar member comprising: a shank member extendinglongitudinally between a proximal end portion adapted to be grasped andpulled by a user and a distal end portion, said shank member having twolongitudinally extending edges thereto; said distal end portion of saidshank member having foot members, at least one extending transversely toeach side of the shank member, which foot members are securedsubstantially symmetrically with respect to the longitudinal axis of theshank member to said one or more wall panels, said foot members having aproximal edge which extends from said longitudinal edge of said shankmember; said shank member having a point of rotation about which theshank member is adapted to flex, said point of rotation being locatedlongitudinally with respect to the shank member substantially inregister with the junction of said longitudinal edges of the shankmember and said proximal edges of said foot members; and in that saidsecurement means of each of the foot members extends longitudinally adistance d distally beyond the point of rotation and a distance d′proximally short of the point of rotation and the ratio of d:d′ has avalue of from 10:1 to 1:10.
 17. A pull tab for use upon a container orblank as claimed in either of claim 1 or 7, characterized in that thepull tab is a generally planar member and comprises: a shank memberextending longitudinally between a proximal end portion adapted to begrasped and pulled by a user and a distal end portion, said shank memberhaving two longitudinally extending edges thereto; said distal endportion of said shank member having foot members, at least one extendingtransversely to each side of the shank member, which foot members areadapted to be secured substantially symmetrically with respect to thelongitudinal axis of the shank member to said container or blank, saidfoot members having a proximal edge which extends from said longitudinaledge of said shank member; said shank member having a point of rotationabout which the shank member is adapted to flex, said point of rotationbeing located longitudinally with respect to the shank membersubstantially in register with the junction of said longitudinal edgesof the shank member and said proximal edges of said foot members; eachof the said foot members extends longitudinally a distance d distallybeyond the point of rotation and a distance d′ proximally short of thepoint of rotation and the ratio of d:d′ has a value of from 10:1 to1:10.
 18. A pull tab as claimed in claim 17, characterized in that theincluded angle between the proximal edge of the foot member and thelongitudinal axis of the shank member is from 15 to 80°.
 19. A pull tabas claimed in claim 17, characterized in that the pull tab is made froma laminate of two polymeric materials, one having a fusion temperatureat least 40° C. higher than the fusion point of the other.
 20. A pulltab as claimed in claim 19, characterized in that the pull tab is madefrom a laminate of polyester and polyethylene.